Week -2
1. Simulink model of Doorbell using solenoid block
This Model contains a solenoid block, switch, battery and transilational motion sensor. Switch is controlled by an input pulse signal with 4 sec period and 2 sec (50% of period) pulse width. So the switch will on for 2 sec and off for 2 sec. Movement of plunger in solenoid is measured using Ideal transilational motion sensor. The results are given below.
Results :
As the input goes high the switch get closed. Plunger will moved to the bottom position, thats shown in 0-2 sec. When switch is released due to zero value in input pulse plunger will move back and get into a steady state.Some oscillating movement is seen in plunger position due to the momentum of plunger. 2-3 sec the plunger is in its steady state.
2. Use a thermistor to sense the temperature of a heater & turn on or turn off the fan as per the below conditions:
Temperature source: 20 °C from 0 to 10 seconds, 27 °C from 10 to 30 seconds, 23 °C from 30 to 50 seconds
Fan conditions: ON if the temperature above 25 °C, OFF otherwise
This model contains a heater representation using Controlled temperature source. The Input signal for controlled heating is provided using Repeating Sequence Stair signal. Input values are 20, 27, 27, 23 and 23 with sample time 10s. So first 10 sec the temperature will be 20 and next 20 sec (10 sec to 30 sec) it will be 27 and finally last 20 sec(30 sec to 50 sec ) it will be 23. Temperature value is measured using a Temperature sensor. A load resistor is connected across the thermistor and battery arrangement and a voltmeter will measure the voltage across the load resistor. Which is proportional to the temperature change. Change temperature varies the resistance of the thermistor hence the voltage across the load resistor. The threshold voltage value for 25 degree celsius is measured and the value is set in switch threshold. Whenever the input voltage to switch is greater than threshold (equvalent to 25 degree celsius) the switch will close and output will get a value of 1. Else switch will be opened and hence output will be 0. Which can be used to controll the fan.
Input parameters:
Switch parameters:
Result :
The first 10 sec input temperature is 20 degree celsius, which is less than the threshold value. Hence the fan is off (out value =0). Next 20 sec temperature value is equal to 27 degree celsius (Greater than threshold) So the fan is on(out =1). Next 20 sec the input temperature value is 23 degree celsius, which is also less than the threshold value. So the fan is in off condition (Out =0).